Natural gas is often extracted by a natural gas producer from a subterranean formation and transported to various end users through a pipeline distribution network. Because the end users of the natural gas may be located a great distance from the wellhead (source), it is common for main distribution line pressures to be on the order of about 1000 pounds per square inch (psi) or greater.
Local gas distribution companies often purchase natural gas from a natural gas producer. The local distribution companies take delivery of the natural gas from the main distribution lines and in turn distribute the gas to various residential and commercial consumers via a secondary, local network. The distributed gas may be at significantly reduced pressure levels, such as on the order of a few psi.
While main distribution line pressures may be around 1000 psi, the pressure of the extracted natural gas from a wellhead may be significantly greater, such as from 5,000 to 15,000 psi or even higher. It is common to use a pressure reducing mechanism, such as a choke, to reduce the wellhead pressure level (e.g., 10,000 psi) to a suitable main distribution line pressure level (e.g., 1000 psi). Because of Joule-Thompson cooling, the reduced pressure gas may undergo a significant drop in temperature, and liquid content (such as water) in the gas may freeze or otherwise impede the transfer of the natural gas into the distribution network.
A related issue with the extraction of natural gas is that wellsites are often provided in remote locations. It is common to extract natural gas from an undersea formation using a drilling platform located over a continental shelf (e.g., in the Gulf of Mexico), or in a rural area such as in the middle of a prairie or desert. In such cases, it may be difficult to obtain electrical power to service the needs of personnel and equipment located at or near the wellsite.